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Carbon sink reduction by fruit removal triggers respiration but not nitrous oxide emissions from the root zone of cucumber
Author(s) -
Nett Leif,
Hauschild Ingo,
Kläring HansPeter
Publication year - 2019
Publication title -
annals of applied biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.677
H-Index - 80
eISSN - 1744-7348
pISSN - 0003-4746
DOI - 10.1111/aab.12516
Subject(s) - nitrous oxide , shoot , carbon dioxide , dns root zone , sink (geography) , respiration , aeration , biology , greenhouse gas , agronomy , horticulture , carbon sink , denitrification , botany , chemistry , nitrogen , irrigation , ecology , ecosystem , cartography , organic chemistry , geography
Root exudation of organic carbon (C) is generally believed to be the cause of positive effects of root activity on nitrous oxide (N 2 O) emissions. We tested the effects of root exudation in an actual soil–plant system on N 2 O emissions while excluding most other potential factors. The C source/sink ratio in cucumber was changed by removing fruits to increase root exudation. Root‐zone emissions of carbon dioxide (CO 2 ) and N 2 O were monitored in complete stands of adult plants in a greenhouse. Whereas CO 2 emissions rapidly increased as a result of fruit removal the N 2 O emissions were completely unaffected. After cutting the shoots CO 2 emissions decreased within 2 weeks in both the fruit removal treatment and the control to a value significantly lower than that before the start of the treatments. However, N 2 O emissions immediately exhibited a short peak, which was significantly higher in the fruit removal treatment compared to the control. Thereafter N 2 O emissions in both treatments remained on the same level but considerably higher than before shoot cutting. We concluded that in a well‐aerated root zone, a root exudation pulse does not necessarily increase N 2 O emissions, because C substrates are quickly respired by microorganisms before they can support heterotrophic denitrification. The results further indicate the significance of dying/dead roots for the creation of denitrificaton hot‐spots, which likely result from providing C substrates as well as poorly aerated habitats.